Calcium dipropionate

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013-04-15 to 2013-04-18

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

two vessels were set up in a parallel design at 20 ± 1.0 °C, each vessel was sampled several times instead of sampling one vessel at every point in time

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

two vessels were set up in a parallel design at 20 ± 1.0 °C, each vessel was sampled several times instead of sampling one vessel at every point in time

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2011-02-07

Type of method:

flask method

Remarks:

analysis via ICP-OES

Water solubility:

62.1 g/L

Conc. based on:

element (dissolved fraction)

Remarks:

Ca

Loading of aqueous phase:

1 435 g/L

Incubation duration:

3 d

Temp.:

20 °C

pH:

6.6

Remarks on result:

other: dissolved Ca from day 2 until day 3 at a loading of ca 1435 g calcium propionate/L

Water solubility:

289 g/L

Conc. based on:

test mat. (dissolved fraction)

Loading of aqueous phase:

1 435 g/L

Incubation duration:

3 d

Temp.:

20 °C

pH:

6.6

Remarks on result:

other: calculated dissolved calcium propionate from day 2 until day 3 at a loading of ca 1435 g/L

Details on results:

Observations
During the study, undissolved test material was observed in the media in the flasks. After filtration, the solutions were clear. In order to verify this, the turbidity was measured in filtered samples.

Temperature
The temperature in the thermostatically controlled water bath was monitored by a Testo 175-T2 thermo datalogger. The mean temperature was 20.7 ± 0.1°C

 Monitoring oxygen concentration
During the experimental performance of the test, the oxygen concentration in the acrylic glass box was monitored with a MICRO IV oxygen sensor prior and after sampling. The oxygen values (in %) remained around 0 %. Slightly negative values, though impossible, are due to measurement uncertainties of the device at 0 % oxygen.

Solution pH
Solution pH in method blanks ranged from 5.5 to 6.1, whereas the pH in samples containing the test item increased to 6.4 – 6.8. The temperature measured by the pH meter is not within 20.0 ± 1.0 °C. Considering the pH values the pH meter is calibrated every workweek and verified every working day. A calibration of the temperature was not performed because a Testo 175-T2 thermo data logger was applied during the test

Turbidity
The turbidity was measured after centrifugation and filtration to verify that only dissolved calcium concentrations would get measured. The turbidity was always < 1 NTU, indicating that there was not any undissolved material and micelles did not form after the filtration and centrifugation step.

Dissolved calcium concentrations
Dissolved calcium concentrations in all method blanks (28.36 – 45.58 µg Ca/ L) sampled at each sampling point were above the limit of quantification LOQ = 0.067 µg Ca/ L. However, compared to concentrations in test item loaded samples the Ca amount in method blanks is << 0.1 %.
Test samples were diluted (dilution factor 1,000,000) so that the respective Ca concentrations would be in the calibrated range of the ICP-OES instrument. Constant calcium concentrations as defined by the study guideline OECD 105 and the Regulation 440/2008/EC A.6 were measured from day 2 until day 3.

 Method validation summary

validation parameter	results	comment
selectivity	similar data with at least three different calcium wavelengths for ICP-OES method	no interferences due to test media observed
linearity	applied calibration functions were linear	correlation coefficient at least 0.999405
limits of detection (LOD)	0.067 µg Ca/L
limits of quantification (LOQ)	0.202 µg Ca/L
method blanks	above LOQ but far below conc. in actual samples (<< 0.1%)
accuracy and precision	mean recovery for multielement standard solution VIII (50 µg Ca/L): 101 ± 4 % (n = 4)	for concentration range
accuracy and precision	mean recovery for quality control standard (500 µg Ca/L): 97.2 ± 0.4 % (n = 4)	for concentration range
accuracy and precision	mean recovery for recalibration samples (100 µg Ca/L): 99.9 ± 1. 3% (n = 4)	for concentration range
trueness	recovery from fortification of samples: 94.0 – 96.4 %
repeatability	mean recovery for multielement standard solution VIII (50 µg Ca/L): 101 ± 4 % (n = 4)	for concentration range
repeatability	mean recovery for quality control standard (500 µg Ca/L): 97.2 ± 0.4 % (n = 4)	for concentration range
repeatability	mean recovery for recalibration samples (100 µg Ca/L): 99.9 ± 1.3 % (n = 4)	for concentration range

 

Constant calcium concentrations were measured from day 2 until day 3, i.e. calcium concentrations varied were less than 15 % between sampling points. Therefore, the acceptability criteria of the study guideline OECD 105 and the Regulation 440/2008/EC A.6 could be regarded as fulfilled.

The mean dissolved calcium concentrations of solutions sampled from day 2 until day 3 were calculated.

Mean dissolved Ca concentrations day 2 – day 3:

Vessel 1: 63.9 ± 3.9 g Ca/L

Vessel 2: 60.5 ± 3.0 g Ca/L

The amount of calcium propionate dissolved was calculated based on the metal content of the test substance as follows:

 = mean of measured Ca concentration * 100 % / 21.5 % [Ca content of test item]

mean calculated calcium propionate dissolved day 2 – day 3:

Vessel 1: 297.0 ± 18.1 g/L

Vessel 2: 281.4 ± 14.0 g/L

Conclusion

Under the conditions of this test (under exclusion of CO2 and O2, under inert argon gas; flask method; loadings of 1435.074 and 1435.039 g/L in vessel 1 and 2, respectively),a solubility equilibrium was reached from day 2 until day 3 of testing. The mean amount of dissolved Ca from day 2 until day 3 at 20.0 ± 1.0 °C is 62.1 ± 3.7 g/L (determined as dissolved Ca, separated by filtration from undissolved test item). This corresponds to a calculated water solubility of dissolved calcium propionate of 289.0 ± 17.2 g/L at 20 °C / pH 6.6, calculated based on a metal content of 21.5 %.Solution pH in method blanks ranged from 5.5 to 6.1, whereas the pH in samples containing the test item increased to 6.4 to 6.8.

Conclusions:

Interpretation of results (migrated information): very soluble (> 10000 mg/L)
The test item calcium dipropionate has a water solubility of 289.0 ± 17.2 g/L at 20 °C and pH 6.6.

Description of key information

Calcium dipropionate has a water solubility of 289.0 ± 17.2 g/L at 20 °C and pH 6.6.

Key value for chemical safety assessment

Water solubility:

289 g/L

at the temperature of:

20 °C